Which of the Following Statements About Questionnaire Design Is True

Which of the following statements about questionnaire design is True?

A) Sensitive questions like those concerning the respondent's age or personal hygiene is generally placedat the very end of the questionnaire.
B) The hardest questions should be first, and the easiest ones at the end so that the answering process will draw to a close rapidly in case respondent wants to quit.
C) To remove interviewee bias, open-ended questions should be used only in mail surveys.
D) Questions should contain some flexibility to accommodate the interviewers' styles.
E) None of the above statements about questionnaire design is True.